Apparatus for melt spinning of synthetic filaments



" KAM E Kl 3H l SHIBAY ETAL I 3,512,214

7 May 1.9, 1970 APPARATUS FOR MELT SPINNING OF SYNTHETIC FILAMENTs Filed July 8. 1966 F I6. I

F 2 mmazy wa TETSUO ZAM'AK/ BY RYO/CH/PO PUMA/(0.57 4 w A? A r mxqw m United States Patent M 3,512,214 APPARATUS FOR MELT SPINNING OF SYNTHETIC FILAMENTS Kamekichi Shiba and Tetsuo Tamaki, Ehime-ken, and Ryoichiro Funakoshi, Tokyo, Japan, assignors to Fuji Spinning (30., Ltd., Chuo-ku, Tokyo, Japan Filed July 8, 1966, Ser. No. 563,745 Claims priority, application Japan, July 8, 1965, IO/40,595 Int. Cl. D01d 13/02 US. Cl. 18-8 5 Claims ABSTRACT OF THE DISCLOSURE An apparatus for melt spinning of synthetic filaments includes a heater for melting the resin, and a pump or other means for forcing the melted resin through a spinneret to form filaments. An infrared ring-shaped heater fuses the filaments. They are then cooled in a cooling bath.

This invention relates to apparatus for the melt spinning of synthetic filaments.

In the manufacture of polyvinyl chloride filaments by melt spinning, drawing of the filaments in a hot spinning cylinder, so-called spin-drawing, has been known. In this method a slender and hollow porcelain cylinder, for instance, 5 centimeters in diameter and 35 centimeters in length, is positioned at the upper part of the spinning cylinder below a spinneret. A nickel-chromium resistance wire is wound around the cylinder for heating the porcelain cylinder up to 600 C. in the center. However, this device produces a wide temperature distribution in the spinning cylinder. The spinning cylinder is open at its lower end to the atmosphere, which is at a lower temperature. The filaments emanating from the spinneret are instantly heated and fused in the porcelain heating cylinder and are subjected to drawing by viscous drag and traction of fused high molecular materials so that greatly elongatable fine-denier filaments with an unorientated molecular structure are continuously obtained. However, the heating and fusing parts of this system present difficulties in uniform and concentrated heating because of the wide temperature distribution. In particular, in a commercial scale of production, when a large number of filaments run parallel at high speed with considerable vibrations, the drawing action may be variable in space and time and the filaments may be accordingly drawn with serious irregularities.

Furthermore, the high molecular substances (including various contained additives, for example, thermal stabilizers) forming the filaments, when heated and fused will vigorously evolve volatile decomposed gases when heated and fused at elevated temperatures. These undesired products tend to choke the spinneret openings or become deposited on the inner wall of the heating cylinder, thus rapidly deteriorating the heating effect of the device. It is therefore particularly important for continuous operation on a commercial scale to positively exhaust and eliminate such decomposed gases, usually from the upper portion of the spinning cylinder. In case of rapid evolution of gases, the filaments in the unsolidified or soft state which are processed through the heating cylinder are badly oscillated by the stream of exhaust gases being discharged. The oscillation of the filaments results in uneven drawing and mutual contact and sticking of filaments, resulting in adverse effects upon their quality and denier size. When a high degree of drawing is required to produce highly at- 3,512,214 Patented May 19, 1970 tenuated filaments, the spinning rate (linear velocity at which the filaments run) after drawing is also remarkedly increased over the usual rate. The higher is the spinning rate, and accordingly the longer the spinning cylinder required, the more vigorously the filamentswill oscillate. This tendency to vibrate at high speed makes the countermeasures all the more important.

The overall length of the spinning cylinder must be markedly increased in proportion to the increase in the spinning rate in order to cool and solidify the filaments inside the spinning cylinder. Such cooling is accomplished with air drawn in from the bottom of the cylinder.

In an alternative arrangement, wherein the cooling is not accomplished by air but by water, a horizontal cooling water channel is provided below the bottom of the spinning shaft. The filaments which are not fully solidified are wound on a yarn guide prior to their cooling in order to be transported to the water channel. The filaments are likely to be deformed or damaged by the contact with the yarn guide and are subjected to the substantially increased viscous drag of the bath liquid with the result that highspeed spinning is not achieved.

It is the objective of the present invention to provide a. relatively inexpensive machine and system for melt spinning of filaments in which: (1) the filaments are kept separate from each other and do not contact the ma chinery until they are solidified, (2) the filaments may be drawn at high speed, (3) the heating of the filaments does not evolve gases and by-products which clog the spinneret and cause the filaments to contact each other, and (4) the filaments may be cooled without touching each other or the machinery.

In accordance with the present invention, a large number of parallel running filaments of high-molecular substances are extruded from spinneret openings and are highly drawn by heating and fusing simultaneously and instantly by the use of a ring-shaped infrared ray heater. The stretching of filaments, which in a soft or semi-soft state, is used often for the relief of their inner strains; see Schmidlin, Preparation and Dyeing of Synthetic Fibers (Eng. edition, 1963) at pp. 25-27 and 36. Preferably the heater is circular and uniform in cross-section. This ring-shaped heater has a far lower drag against the decomposed gases which are being exhausted than the slender and hollow cylindrical type previously used. This lower drag results in less air turbulence. The volatile decomposed gases are exhausted effectively without causing sticking or contact among the filaments. This prolongs the life of the spinneret, which must otherwise be re placed due to clogging of the openings. The filaments in their unsolidified (soft state) are cooled solid by water without any alteration in their axial direction in a vertically aligned cooling tank. The cooling water positively supports the filaments from sidewise vibration and permits the use of a shorter spinning cylinder.

Thus, one embodiment of the invention is characterized in that filaments emerging from the spinneret are momentarily heated and fused by a ring-shaped infrared ray heater which is circular in section. \Another embodiment of the invention is characterized as comprising one or a plurality of ring-shaped infrered ray heaters which are disposed at suitable intervals in the upper portion of a spinning cylinder and an inverted truncated conical tank for cooling liquid which is provided underneath the spinning cylinder and in the same axial direction as the fibers which emanate from said spinning shaft.

Other objectives of the present invention will be apparent from the detailed description of the preferred embodiments, as set forth below, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of a melt spinning apparatus formed in accordance with this invention; and

FIG. 2 is a sectional view taken along the line 22 of FIG. 1.

In the figures shown, a spinneret 1 is positioned at the top of a spinning cylinder 2. One, or a plurality, of infrared ray heaters 3 is positioned at the inside of the upper portion of the spinning cylinder 2. Each heater consists of an annular quartz tube having a circular section and containing a nickel-chromium resistance wire, i.e., a Nichrome wire, hermetically sealed therein. If a plurality of heaters are used they are disposed at suitable intervals at the top of the cylinder 2.

The inner wall of the spinning cylinder 2 surrounding the infrared ray heater 3 is provided with a large number of exhaust ports 4. These ports 4 communicate outward- 1y, through circular perforated or porous plates 5, to an exhaust duct 6. The duct 6 leads the exhaust gases which are pumped to the outside. An air intake rectifier plate '7, i.e., a perforated gas turbulence damping plate, is attached at the bottom of the cylinder 2. A jacket 8, for heat insulation, is mounted on the top of the cylinder 2.

Below the bottom of the cylinder 2, there is provided an inverted truncated conical water tank 10. Tank has a small Water releasing orifice 9 at its bottom. Tank 10 is fully open at its top. The water from orifice 9 is collected in a tank and recirculated. The water in the tank 10 which is released through the orifice 9 is replenished by Water from feed pipe 11. The water is caused to overflow beyond the top edge of the tank 10, so that the cooling water can be supplied and maintained at a constant level. The overflow water is collected by an overflow tank 12 and is drained through an overflow return pipe 13. The pipe 13 may be connected to the feed pipe 11 for recirculation and reuse of the water after its purification or other treatment. A stretching roll 14 and a winding roll 15 are positioned after tank 10 to stretch and Wind the bunch of filaments being wound up.

In the use of the present invention the filaments are usually in the fused state immediately after discharge from a spinneret. At that point they have such a high transmissivity to heat rays that, when heated by irradiation with infrared rays from infrared heaters of the construction as above described, they can be instantly and uniformly heated, not merely on the surface, but to their very cores. Moreover, the heaters of the present invention obtain a good thermal efliciency, because direct heating of the filaments is possible Without any wasteful heating or temperature rise of the atmosphere surrounding the filaments. The temperature control of the heaters for the prevention of decomposition and deterioration of the material by excessive heat is achieved electrically with ease. Consequently, the heaters are suitable heating sources for effecting a high degree of drawing. The infrared rays emitted by the resistance wire, according to the invention, are irradiated through quartz glass having an extremely high transmissivity to infrared rays. The infrared radiation is therefore more intense and uniform in wavelength distribution than are the heat rays emitted from the unglazed porcelain cylinder, mentioned above, which has a lesser transmissivity to infrared rays. As the infrared heater of the invention is ring-shaped with a circular cross section, is provides a heating and fusing zone for the filaments in which the temperature distribution is more uniform compared to the slender hollow cylinded mentioned above, and thus accomplishes effective heating uniformly and concentrically in space. The volatile decomposed gases are evenly exhausted by the action of the annular porous resistance plates when they are discharged, together with the air flowing in through the air intake rectifier plate, into the exhaust duct by -way of the exhaust ports. This feature, combined with the ringshaped configuration of the infrared heater, which has little fluid resistance because of the circular cross sec tion and the arrangement at suitable intervals where employed in a plural number of pieces, minimizes the turbulence of the exhaust gas stream and the oscillation of the filaments leaving the spinneret.. Therefore, the exhaust efliciency is improved and deposition of exhaust components on the surface of spinneret, infrared heaters, etc., can be prevented.

The highly drawn filaments, still in the unsolidified or soft state, are passed through the cooling liquid tank without any alteration in the axial direction of the filaments. They are allowed to run together with the cooling water, past the water releasing orifice, so that they can be rapidly cooled to their solid state by the water. The cooling bath itself serves to inhibit or damp the swinging of running filaments. This eliminates the need of guides for the filaments, and hence precludes any possibility of deformation or damage of the filaments.

The filaments are discharged together with the cooling water. At that point, i.e., at orifice 9, the filaments are solidified and Wound around a stretching roll 14. The roll 14 carries them in a direction tangential to their original direction. The filaments are then wound at a high speed on a winding roll 15. Thus, the heating device which consists of a spinning cylinder equipped with infrared heaters on the upper part thereof and the cooling device consisting of a cooling tank of the type above described have their own individual merits. In addition, if both devices are combined, one may attain all the more improved effects in accomplishing high drawn melt spinning efficiently in a short spinning apparatus. Because the spinning cylinder is short in height means that the overall spinning equipment becomes small in size. Accordingly, the cost of construction is lower and the handling is easier.

The high-molecular substances useful in the invention include not only homopolymers such as polyvinyl chloride, polypropylene, and polyethylene, but also copolymers and mixtures thereof. Even a mixture containing a component which is particularly prone to be thermally decomposed or consisting of components which differ in the fusing point or softening point, can be produced to highly drawn good-quality synthetic filaments by the instant intensive heating accomplished in accordance with the invention, if the mixture is extruded beforehand by an extruder or other means through a spinneret into filaments.

The invention is illustrated by the following examples. This invention, however, is not intended to be restricted by these examples, which are illustrative of the operation of the present invention.

EXAMPLE 1 To one thousand parts of a commercially available polyvinyl chloride resin (With a nominal mean polymerization degree of 800), 25 parts each of dibutyl tin dilaurate and dibutyl tin maleate (as thermal stabilizers) and 20 parts of bis-stearic amide (as a lubricant) were added. The mixture was extruded by an extruder having a screw, 30 mm. in diameter, and spun through a spinneret having holes each 1.5 mm. in diameter and 1.5 mm. in effective length, at a temperature of C. and a spinning rate of 400 mm. per minute. The filaments leaving the spinneret were heated by a 2.0 kw. ring-shaped infrared heater which had a circular tube 20 mm. in the cross sectional diameter and mm. in the ring diameter (or three 0.75 kw. heaters spaced in a distance of 20 mm. from one another) and which was disposed 30 mm. below the spinneret. The temperature of the central heating area on the plane including the ring of the infrared heater (hereinafter referred to as the infrared area) was 290 C. A cooling tank provided below the spinning cylinder (at a distance of 80 cm. from the heater) was supplied with water. at normal temperature at a rate of 3 liters per minute. The filaments were thereafter oiled and wound up at a rate of 1800 m. per minute. The fibers thus obtained the following good properties:

Size, deniers 3.02

Elongation, percent 48.2

Tensile strength, g./denier 2.98

Contraction in boiling water, percent 10.2

EXAMPLE 2 A commercially available polypropylene resin (with a nominal mean molecular weight of 60,000) was spun into filaments in the same manner as described in Example 1, with the exception of the following conditions:

The material was extruded through an extruder and spun through a spinneret having five holes each 1.5 mm. in diameter, at a temperature of 192 C. and at a spinning rate of 500 mm. per minute. The filaments were then passed through the infrared area kept at 210 C. for drawing and were wound up at a rate of 800 m. per minute. The fibers thus obtained had a size of 2.56 deniers, tensile strength of 4.2 g./d., and ultimate elongation of 52%.

EXAMPLE 3 A commercially available polyethylene resin (with a nominal mean molecular weight of 40,000) was spun into filaments in the same manner as in Example 1, with the exception of the following conditions: by the use of a spinneret having 30 holes each 1.5 mm. in diameter, the material was extruded through an extruder at a temperature of 145 C. and at a rate of 600 mm. per minute. The filaments were then drawn at an infrared area temperature of 280 C. and wound up at a rate of 1400 in. per minute.

The fibers thus obtained had a size of 2.83 deniers, tensile strength of 2.9 g./d., and elongation of 43%.

EXAMPLE 4 A commercially available polycarbonate resin (with a nominal mean molecular weight of 30,000) was spun into filaments in the same manner as in Example 1, with the exception of the following conditions: The material was extruded through a spinneret having holes each 0.7 mm. in diameter, at a spinning rate of 500 mm. per minute and at 225 C. The drawing temperature of the infrared area was 275 C. and the filaments thus produced were wound up at a rate of 800 m. per minute.

The fibers obtained had a size of 2.5 deniers, a tensile strength of 2.8 g./d., and an elongation of 42%.

EXAMPLE 5 A commercially available ABS (acrylonitrile-butadienestyrene) resin was spun into filaments in the same manner as in Example 1, with the following exceptions: The ABS resin was extruded through a spinneret having five holes. Each hole was 1.5 mm. in diameter. The spinning rate was 400 mm. per minute and the temperature was 170 C. Drawing of the filaments was effected at the infrared area and their temperature kept at 225 C. during such drawing. The filaments were wound up at a rate of 400 m. per minute. The fibers obtained had a size of 5 deniers, a tensile strength of 2.1 g./d., and an elongation of 32%.

We claim:

1. Apparatus for the melt spinning of synthetic fibers in which the filaments of the fibers are drawn from a spinneret, the apparatus comprising a vertically aligned cylinder having a plurality of exhaust ports near its top; a spinneret positioned at the top of said cylinder; a ringshaped infrared heater positioned beneath the spinneret and inside said cylinder in the area of the cylinder which contains the exhaust ports; an exhaust chamber surrounding that portion of the cylinder containing the exhaust ports, said exhaust chamber comprising a plurality of concentric porous ring-shaped plates and an outermost ring-shaped plate having a duct port therein.

2. Apparatus as described in claim 1, further including a cooling tank adapted to hold cooling fluid positioned beneath the heater, said tank being vertically aligned and having an opening at its top and an orifice at its bottom for the passage of said filaments.

3. Apparatus as described in claim 1, further including a gas-damping plate positioned at the bottom of said cylinder.

4. Apparatus as described in claim 2, further including a feed pipe extending to said opening of the tank to supply a cooling liquid to overflow the top of said tank, and an overflow tank to collect the liquid overflow from the top of said cooling tank, said overflow tank having an overflow return pipe communicating with said feed pipe for recirculation and re-use of the cooling liquid.

5. Apparatus as described in claim 2 wherein said tank is in the shape of an inverted, truncated cone.

References Cited UNITED STATES PATENTS 1,202,766 10/1916 Althouse 1'8--8 1,683,478 9/1928 Neidich 188 2,161,354 6/1939 Imray et a1 18-8 X 2,335,922 12/1943 Dreyfus.

3,053,611 9/1962 Griehl 18'8 X 2,542,973 2/1951 Abernethy 188 2,543,027 2/ 1951 I ones 188 3,448,185 6/1969 Sims 18-8 X 2,296,202 9/ 1942 Hardy 188 2,318,679 5/ 1943 Dreyfufs 18-8 2,953,428 9/ 1960 Hunt et al. 18-8 3,040,377 6/ 1962 Slayter et a1. 18-8 3,215,486 11/1965 Hada et a1 264-2l0 X 3,296,352 1/1967 Riggs 264-210 X 3,361,859 1/1968 Cenzato 264-176 FOREIGN PATENTS 5,263 -6/ 1962 Japan.

WILBUR L. McBAY, Primary Examiner 

